The Checklist Manifesto: How to Get Things Right, by Atul Gawande
One of the simplest yet most powerful books you'll read. This book proves something we've suspected for a long time. Writing lists down removes stress, allows you to take action faster and more importantly ensures you get the job done accurately. In the case of investing and business, this leads to maximizing your profits. Check this one out when you're feeling a little overwhelmed with stuff to get done.